Mitosis vs Meiosis: Differences and Cytokinesis Mechanisms

Mitosis and Meiosis Comparison

Similarities Between Mitosis and Meiosis

• The sequence of changes in the nucleus and cytoplasm.
• The presence of the stages of prophase, metaphase, anaphase, and telophase.
• The spindle formation and the cycle of condensation of chromosomes.

Key Differences Between Mitosis and Meiosis

• Mitosis occurs in somatic cells, while meiosis is restricted to germ cells.
• In mitosis, each cycle of DNA replication is followed by one division. The resulting daughter cells are diploid (2n) and have the same amount of DNA as the parent cell.
• In meiosis, one DNA replication cycle is followed by two divisions, resulting in four haploid (n) daughter cells, which contain half the DNA of the parent cell.
• In mitosis, each chromosome behaves independently. In meiosis, homologous chromosomes are linked (pairing) during the first meiotic division.
• Mitosis is typically short (one or two hours), whereas meiosis is a long process. (For example, in humans, meiosis can last 24 days in males and years in females.)
• A fundamental difference is that in mitosis, the genetic material remains constant. However, one of the main consequences of meiosis is genetic variability.

Cytokinesis: Cell Division Completion

Cytokinesis in Animal Cells

In animal cells, narrowing occurs at the cell surface in the equatorial plane, forming the cleavage furrow (or line of segmentation). In the subcortical area, a concentric groove forms due to the organization of a bundle of microtubules, constituting the contractile ring. This ring is responsible for deepening the furrow.

The cytoplasmic organelles are distributed evenly between the two cell portions. Finally, the two cells are connected by a narrow filament before completely separating.

Cytokinesis in Plant Cells

In plant cells, the rigid cell wall prevents the formation of a cleavage furrow. Instead, a new wall forms between the daughter cells.

This new wall is formed by the alignment of vesicles originating from the Golgi apparatus. These vesicles fuse their membranes to form the cell plate between the two daughter cells.

Cytoplasmic bridges, known as plasmodesmata, exist between the two cells.

The ends of the cell plate membranes eventually fuse with the existing cell membrane, completing the separation of the two daughter cells.